Azalea plant named ‘Robleja’

ABSTRACT

A new and distinct variety of  Azalea  plant named ‘Robleja’, characterized by its unique blooming time, upright, dense and globose growth habit, and attractive single to semi-double flowers which change from pink to white.

Genus species: Rhodendron hybrid.

Varietal denomination: ‘Robleja’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct variety of evergreen Azalea of the genus Rhododendron and a member of the Ericaceae family. This new Azalea variety, hereinafter referred to as ‘Robleja’, was discovered by Robert Edward Lee in August, 1998 in Independence, La. ‘Robleja’ originated from a controlled breeding program in Independence, La. The objective of the breeding program was to create new Azalea varieties which have unique blooming periods, bloom colors, bloom forms, bloom sizes, and growth habits. ‘Robleja’ originated from a cross made by Mr. Lee in April, 1996 of the cultivar ‘Watchet’ (unpatented) as the female, or seed, parent with the Azalea hybrid ‘Conleb’ U.S. Plant Pat. No. 10,581 as the male, or pollen, parent.

Asexual propagation of the new plant by cuttings has been under Mr. Lee's direction at the same location. The new plant retains its distinctive characteristics and reproduces true to type in successive generations. The plant cannot be reproduced true from seed.

SUMMARY OF THE INVENTION

The following are the most outstanding and distinguishing characteristics of this new cultivar when grown under normal horticultural practices in Independence, La.

-   -   1. The unique spring, summer, and fall blooming.     -   2. A pink flower color Red-Purple Group 62B changing to White         Group 155D.     -   3. Single to semi-double flowers ranging in size from 2″ to 2½″         in diameter.     -   4. Easily propagated with semi-hardwood cuttings in late spring         through the summer.     -   5. Fast growth rate under normal fertilization and moisture         conditions.     -   6. Upright, dense and globose in nature.     -   7. Good specimen plant.     -   8. Desirable in planters.     -   9. Makes a very good hedge or screen.     -   10. Very good foundation plant.     -   11. Does well as an understory plant in a woodland garden.     -   12. Hardy to Zone 7.     -   13. Attracts butterflies.

DESCRIPTION OF THE DRAWINGS

This new Azalea hybrid variety is illustrated by the accompanying photographic prints in which:

1. The photograph at the top of the sheet is a close-up showing flower, foliage, and stem color as well as flower size and form.

2. The photograph at the bottom of thr sheet shows the upright, dense and globose growth habit of a young three gallon plant.

The colors shown are as true as is reasonably possible to obtain by conventional photographic procedures. Colors in the photographs may appear different than actual colors due to light reflectance. The colors of the various plant parts are defined with reference to The Royal Horticultural Society Colour Chart. Description of colors in ordinary terms are presented where appropriate for clarity in meaning.

BOTANICAL DESCRIPTION OF THE PLANT

The following is a detailed description of the new variety of Azalea based on my observations made of 2 year old plants grown in 3 gallon containers in wholesale commercial production practices, in greenhouses, and in established landscape plantings in Independence, La.

Distinctive Characteristics

TABLE 1 R.oldhamil ‘Conleb’ ‘Fourth of Characteristic ‘Robleja’ ‘Watchet’ PP#10,581 July’ Height (Mature) 4-5′ 2-3′ 4-5′ 8-10′ Width (Mature) 3-4′ 3-4′ 5-6′ 6-7′ Flower Diameter 2-2½″ 3½-3¾″ 2½-2¾″ 1¾-2¼″ Flower Form Single/ Single Single/ Single semi-double semi-double Flower Color Red Purple Red G. Red G. 44A Red G. 39A G. 62B 49B changing to 155D Flowers per 2-3 1-2 2-3 2-4 Terminal Bloom Period April May April Late June> ″ Late July> Late July> Frost Frost Frost Petal/Petaloid  5-13 5  5-14 5 Number Hardy Zone 7 6 7 7 Stamen Number 5-8 10  0-9 7-10 Stamen Type Some Non- Some Non-Petaloid Petaloid Petaloid Petaloid

The female, or seed parent, of ‘Robleja’ is the Azalea ‘Watchet’; a moderate pink, single, late blooming, low compact grower. ‘Watchet’ is an unpatented Robin Hill hybrid developed by Robert Gartrell in Wycoff, N.J. Mr. Gartrell started his hybridization in 1937 to produce hardy, late blooming azaleas. ‘Watchet’ is the result of a cross between the Satsuki Hybrid ‘Amagasa’ (unpatented) and the Robin Hill Hybrid ‘Lady Louise’ (unpatented).

The male, or pollen, parent of ‘Robleja’ is the Azalea hybrid ‘Conleb’ U.S. Plant Pat. No. 10,581 which was the result of Mr. Lee's planned cross hybridization between the Azalea ‘Watchet’ and Rhododendron oldhamii ‘Fourth of July’ (unpatented). ‘Robleja’ differs from ‘Conleb’ primarily in flower color.

Robert Edward Lee's hybridization program was conducted with emphasis On species that are not commonly found in the genetic make-up of the present day hybrids. The ‘Fourth of July’ cultivar which Mr. Lee obtained from Dr. Thornton in 1981 is a heavy summer and fall blooming plant, not like the Rhododendron Species Foundation form. The flower buds form on new growth and start blooming about July 1. Mr. Lee used this cultivar to cross with existing hybrids which have a tendency to bloom in the fall and which are also fairly hardy. As expected the resulting seedlings are heavy summer and fall bloomers with very impressive spring blooms also.

-   Classification: -   Botanic: Rhododendron hybrid ‘Robleja’. -   Form: Upright, dense, and rounded. -   Height: 4-5′. -   Width: 3-4′. -   Growth habit: Upright, dense and globose. Fast growth rate under     normal fertilization and moisture conditions. -   Growth rate: In a period of six years from a rooted cutting the     plant reaches a height of 3 feet and a spread of 2 feet. The growth     rate is normally about 6 to 8″ per year; the plant reaches a height     of 4 to 5′ at maturity while maintaining a dense habit due to the     abundant branch development. -   Foliage: Alternate, simple, evergreen, pubescent, elliptic, and     varying in size from 1⅝″ to 2⅛″ long and ⅝″ to ⅞″ wide. The margins     are entire, with a petiole 3/16″ to ¼″ long. Midveins and laterals     are impressed on the upper leaf surface and prominent on the     underside. The base of the leaf is cuneate to attenuate and the apex     is acute to mucronate. The upper surface of the immature leaves is     dull, pubescent, and is Yellow-Green Group 144A and the underside is     Yellow-Green Group 146D, pubescent, and matte. The upper surface of     the mature leaves is Yellow-Green Group 147A, glossy and slightly     pubescent and the underside is Yellow-Green Group 146B, matte, and     pubescent. The immature petioles, midribs, and veins are     Yellow-Green Group 146C. New growth is pubescent. These hairs are     initially soft and white and cover both sides of the leaf with a     higher concentration on the petioles and veins. They are slightly     curled, flat, and range in length from 1/64″ to 1/32″. As the growth     matures much of the leaf pubescence is lost; however, the stems,     petioles, and leaf veins retain this pubescence which becomes more     setaceous and darker in color (Brown Group 200B) through the growing     season. The reduction of pubescence makes the leaf appear darker     than Yellow-Green Group 147A.

In 2001, the date of initial spring growth was March 8, in Independence, La. After the initial spring flush there was almost continuous growth until that fall ending November 5, also in Independence, La. When grown in full sun, the internode length of this plant is ⅜″ to ¾″; when grown in light shade the internode length is ⅝″ to 1″. As would be expected a plant grown in shade results in a taller, less dense plant with larger leaves.

The average length of terminal growth of the initial spring flush is about 5″ for a plant in full sun and about 7″ when grown in shade. This growth should not be trimmed since it will produce flowers starting in late July. As the plant continues to grow through the summer and fall more flower buds are produced, which mature and bloom until frost. This remaining growth produces about 4″ to 5″ of height. As cool weather approaches, some of the flower buds become dormant. These buds bloom in April of the next year.

-   Stems: The young stems are Yellow-Green Group 146C and densely     clothed with spreading white glandular hairs. During the second     growing season they become Greyed-Green Group 197B, glabrous and     rugose. The pith is solid and uniform. Young and older stems are     densely branched. -   Buds: Tight buds at ½″ are ovate and acuminate Yellow-Green Group     146D with a hairy pubescence Brown Group 200B. The buds are borne in     clusters of 2 to 3, and are sheathed by a pair of modified leaf     bracts which are from ¼″ to ½″ long, persistent, and Yellow-Green     Group 147A. The pedicel is ⅜″ to ½″ long, pubescent, and Yellow     Green Group 144B. The calyx is ⅛″ to ¼″ long, Yellow-Green Group     144B, funnel shaped, persistent, and pubescent. The five imbricated     sepals are lanceolate and joined at the base to form a cup. As the     buds swell the bud sheath matures to a Greyed-Orange Group 165A,     falls off, and reveals the flower color Red-Purple Group 62B. -   Flowers: Perfect, single to semi-double, glabrous, open funnel     shaped, 2″ to 2½″ in diameter by 1¾″ to 2¼″ in depth, borne on     current season's growth, non-fragrant; they last on the plant in the     garden 5 to 6 days. Flower color is Red-Purple Group 62B upper     surface and Red-Purple Group 62D under surface. After 3 to 4 days     the flower changes to White Group 155D (upper surface and under     surface). There are five true petals which are fused at the base,     elliptic, and have wavy margins. These petals are 1¾″ to 2¼″ long,     ¾″ to 1¼″ wide, and have rounded apexes and entire margins. Three     out of five petals are dotted with Purple-Violet Group 80C. There     are 5 to 8 non-petaloid stamens which are 1¼″ to 1½″ long. The     filaments are Red Group 49D, the anthers are Greyed-Orange Group     167B, and the pollen matures to Yellow Group 11B. The 0-8 petaloid     stamens are from 3/16″ to 1¼″ long, ⅛″ to ½″ wide, and odd shaped.     The margins are entire and the apexes rounded. The pistil is single,     non-petaloid, 1⅜″ to 1⅞″ long and Red Group 49B. The ovary is     densely glandular-setose and has five locules. The capsule matures     in about 5 months, in Independence, La., to about ¼″ to ½″ long; it     has a persistent style, is Yellow-Green Group 146B, and contains     from 100 to 400 nonwinged seeds. Normally fruit set is not heavy.     There is a 2 to 3 week flowering period in April in Independence,     La. Flowering resumes in July as the new buds mature and continues     until frost which can be as late as November or December in     Independence, La. Azaleas blooming at this time of year attract     butterflies in profusion. -   Culture: Grows well in a wide range of conditions, tolerates sun to     shade. Prefers a moist, well-drained soil that is rich in organic     matter. Responds well to mulching and medium applications of     fertilizer; prefers ph 5.0 to 5.5. Very little pruning is needed;     adaptable to container and above ground planters; makes a good     foundation plant or informal hedge with excellent foliage and flower     contrast. Ideal for coastal regions and warmer parts of Piedmont.     Propagated with semi-hardwood cuttings in late spring through the     summer. -   Pests: Lace wing and spider mites can be a problem. 

1. A new and distinct variety of Azaelea plant named ‘Robleja’ as illustrated and described. 